The proposed research will develop a comparative primate model to study the effect of stress on immune responses. Further research is still needed in this area to determine how different types of stressors can influence specific aspects of immune responses. In addition, better animal models are needed because of marked species differences and the difficulties inherent in generating stress paradigms that are comparable to human situations. We propose to study the endocrinological and immunological consequences of mother-infant separation in order to evaluate the effects of a non-invasive stress that occurs under natural circumstances. In the initial studies we will determine the influence of a 7-day separation on the response of mothers and infants to a T independent antigen, polyvinylpyrrolidone. Immune competence will be assessed in control and stressed individuals by measuring immunoglobulin levels. These studies will compare the response of two primate species, the squirrel monkey and the rhesus monkey, because they show dramatically different psychoendocrine responses to stress. Our laboratory has already established a behavioral and hormanal measures for examining the effects of stress on both species. Subsequent research will focus on the potentially beneficial effect of social support during the separation and the minimal separation that could elicit an alteration in immune response.